Gradiometer configuration invariant to laser phase noise and sensor rotations

Abstract

A system for gravity measurement includes one or more atom sources, two or more laser beams, and a polarizing beamsplitter and a retro-reflection prism assembly. The one or more atom sources is to provide three ensembles of atoms. The two or more laser beams is to cool or interrogate the three ensembles of atoms. The polarizing beamsplitter and the retro-reflection prism assembly are in a racetrack configuration. The racetrack configuration routes the two or more laser beams in opposing directions around a loop topology, intersecting the three ensembles of atoms with appropriate polarizations chosen for cooling or interferometer interrogation. The three ensembles of atoms are positioned coaxially when interrogated.

Description

CROSS REFERENCE TO OTHER APPLICATIONS[0001]This application claims priority to U.S. Provisional Patent Application No. 62 / 095,671 entitled GRADIOMETER CONFIGURATION INVARIANT TO LASER PHASE NOISE AND SENSOR ROTATIONS filed Dec. 22, 2014 which is incorporated herein by reference for all purposes.[0002]This invention was made with Government support under DE-AC52-07NA27344 awarded by the United States Department of Energy. The Government has certain rights in the invention.BACKGROUND OF THE INVENTION[0003]Field-capable gravimeters and gradiometers are currently used to measure gravity and gravity gradients for numerous applications including surveys of underground mineral and natural resources, predictions of earthquakes, and global climate research such as monitoring Earth's icecaps and water tables. Primary use comes from oil and mining companies, the defense industry, large-scale government-funded projects such as the National Geodetic Survey (NGS), academic researchers focused on ...

AI Technical Summary

Benefits of technology

The invention is a new technology for measuring gravity and gravity gradients using a laser sensor. The technology is designed to be highly accurate, low in power consumption, and robust against sensor rotations and laser phase noise. The invention addresses the limitations of current fieldable gravimeters and superconducting gravimeters, which are expensive, require frequent recalibration, and have long survey times. The invention is based on a new sensor configuration and a new method for interrogating the sensor. The technical effects of the invention include improved accuracy, reduced cost, and improved fieldability for long-term monitoring.

Problems solved by technology

However, this fieldable instrument suffers from a combination of high cost, high power consumption, frequent recalibration, lack of robustness, and long survey times. For example, the falling mirror wears out after repeated use and requires periodic replacement, limiting sensor utility for long-term monitoring.

However, this “relative” instrument compares gravity values at different locations and is susceptible to measurement drift.

Further the superconducting sensors require cryogenic cooling, limiting their fieldability; cryogenic cooling consumes kilowatts of power and adds substantial size and weight to the sensor.

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